APPENDIX. 



SYNOPSIS OF AMERICAN CRETACEOUS BIRDS. 



The present synopsis contains a list of all the species of birds now 

 known from the Cretaceous deposits of this country. As so many of these 

 are at present represented only by fragmentary remains, and their near 

 affinities are thus more or less uncertain, it seems advisable to arrange the 

 genera in alphabetical order, rather than to attempt a more systematic 

 classification. The list contains nine genera, and twenty species. 



Most of the remains of American Cretaceous birds are from the Eastern 

 slope of the Rocky Mountains. The beds in which they are found are of 

 middle Cretaceous age, and have elsewhere been named by the writer the 

 " Pteranodon beds," from the genus of toothless Pterodactyles (Pteranodon), 

 which occurs in them. Nearly all the specimens discovered in this region 

 were found in Western Kansas, and the remainder, in essentially the 

 same strata, in Texas. 



The bird remains found in the green-sand deposits of New Jersey are 

 from a higher horizon, representing a division of the upper Cretaceous. 

 These remains appear to be all distinct from those in the lower strata 

 of the West. Some of the specimens from this region possess characters 

 more specialized than the earlier forms ; and, as neither jaws nor teeth 

 have yet been detected, it is at present impossible to say whether the 

 eastern species belong to the Odontomithes. This point will doubtless be 

 decided by future discoveries. 



All the beds in which bird remains have hitherto been found, in the 

 American Cretaceous, are marine deposits, and the birds preserved in 

 them appear to have been all aquatic species. 



191 



